A holding member holding an energy storage device is provided with: a first frame including an end member aligned with the energy storage device, and an attachment portion connected to the end member; a second frame including a body aligned with the energy storage device, and an extension extending from the body and extending along the outer surface of the end member; and a plurality of coupling portions that couple the first frame and the second frame in a first direction and disposed in the extension at an interval in a second direction. The attachment portion includes an installation portion that is installed on a fixing surface. The other coupling portion is further apart from a center line extending in the second direction of the end member than a coupling portion closest to the installation portion.